In high pressure fluid pumps having reciprocating plungers, it is necessary to provide a seal around the plunger to prevent the leakage of high pressure fluid. In such pumps, the seal must be able to operate in a high pressure environment, withstanding pressures in excess of 10,000 psi, and even up to and beyond 50,000-70,000 psi.
Currently available seal designs for use in such an environment include an extrusion resistant seal supported by a back-up ring, the back-up ring and seal being held by a seal carrier. However, the tolerances for clearance between the plunger and back-up ring are very difficult to achieve and maintain. Very typically, therefore, the plunger and back-up ring come into contact, generating frictional heating, which in turn causes the seal to fail.
A further drawback associated with current pump and seal designs is that the plunger may be misaligned with an extension rod to which it is coupled and which imparts a linear reciprocal motion to the plunger. The misalignment may cause the plunger to create unnecessary wear on parts such as the seal, which contact the plunger as it reciprocates. The misalignment may also cause the plunger to bend and ultimately break.
Accordingly, there is a need in the art for an improved high pressure seal and plunger assembly, and in particular, an assembly that is simple to manufacture accurately, that will increase the life of the seal and that will align the plunger with the seal and with the driver to which it is coupled. The present invention fulfills these needs, and provides further related advantages.